The "special relationship" between the US and UK has lurched from cordiality to open criticism since Donald Trump entered the White House.
The US president is to visit the UK in July on a working trip, rather than a full-blown state occasion.
He rarely minces his words about UK affairs and as such poses a diplomatic headache for Prime Minister Theresa May as she seeks to forge stronger relations with Brexit looming.
Here are the key moments of his relationship with Britain:
Mr Trump is elected president of the United States, forcing UK politicians to quickly change tack in their handling of the billionaire businessman.
Mrs May congratulates Mr Trump on his victory and says Britain and America will remain "strong and close partners".
Nigel Farage, the former Ukip leader, of whom Mr Trump is an admirer, embarrasses Mrs May by beating her to a meeting with the new president.
The Prime Minister becomes the first world leader to meet the president following his inauguration.
She faces criticism for offering President Trump a state visit just seven days into his presidency.
But they are photographed holding hands outside the White House, and Mrs May gets a significant commitment from the president to Nato.
Mrs May's spokesman says she does "not agree" with Mr Trump's refugee ban, an executive order signed just hours after their meeting, and will make representations if it affects Britons.
Cracks begin to appear in the relationship when Mrs May eventually denounces Mr Trump's travel restrictions on Muslims as "divisive and wrong", echoing statements from her ministers.
And she reportedly pokes fun at the size of Mr Trump's hands, telling a Conservative fundraising party, in response to applause from donors: "Thank you very much for that wonderful reception.
"I don't think I have received such a big hand since I walked down the colonnade at the White House."
Mrs May's spokesman denounces "ridiculous" allegations made by the White House press secretary that GCHQ spied on Mr Trump before the presidential election. The president refuses to give a public apology.
The PM rebukes Mr Trump after intelligence shared with the US in the wake of the Manchester terror attack is leaked to American media.
Mr Trump later describes the PM as "very angry" about the leaks, which prompted British police to temporarily suspend sharing information across the Atlantic, and promises to investigate.
In a bad month for relations, the Prime Minister tells Mr Trump of her "disappointment" at his decision to pull America out of the Paris Accord on climate change.
She then directly condemns Mr Trump's attacks on London mayor Sadiq Khan's handling of the London Bridge terror attack as "wrong".
Mrs May delivers a rebuke to the US president after he claimed the Parsons Green Tube bomber was "in the sights" of Scotland Yard. The Prime Minister said: "I never think it's helpful for anybody to speculate on what is an ongoing investigation."
Mrs May and Mr Trump fall out spectacularly over his retweeting of anti-Muslim videos posted online by the deputy leader of the far-right Britain First group, Jayda Fransen.
The PM said Mr Trump was "wrong" to retweet the videos, and the US president hits back at Mrs May on Twitter by telling her to focus on "destructive radical Islamic terrorism" in the UK, rather than on him.
The US president says he has cancelled plans to travel to the UK to open the new American embassy, hitting out at the location of the project and amid fears of mass protests.
Later in the month, Trump blows hot and cold with the Prime Minister during a trip to the World Economic Forum meeting in Davos.
Following talks with Mrs May, the president appears keen to clear the air about tensions between the two nations, declaring: "We love your country."
But then, in an interview with Piers Morgan, he pours scorn on Britain's approach to Brexit negotiations and says he would take a "tougher" approach with Brussels.
He also says he is prepared to apologise for retweeting posts from Britain First, telling Piers Morgan that he knew "nothing" about the organisation before he shared three of its videos.
- Mr Trump uses the NHS as an example of why universal healthcare should not reach US shores.
The response from Mr Trump is initially ambiguous after Russia is blamed for the nerve agent attack on Sergei Skripal and his daughter but the White House later states it "stands in solidarity" with the UK and joins Western allies in expelling diplomats.
Community heroes are named among Prince Harry and Meghan Markle's wedding guests while potential diplomatic tensions are sidestepped as it emerged US president Donald Trump and other politicians, including his predecessor Barack Obama, have not been invited.
Mr Trump is to visit the UK on Friday July 13. It is not a state visit, as has previously been offered, and protests are expected.